Digital Design Lab CSCE2114 L001-6
Professor: Dr. Pakerson
Lab#1
Introduction
In this lab you will be working with digital integrated circuit (IC) chips using trainer boards as well as VHDL programming using a Field Programmable Gate Array (FPGA) board. Figure 1 shows the PB 505 trainer board that we are using in first two sessions, and Figure 2 shows the ALTERA FPGA board that will be used later in the semester. Figure 1: PB 505 trainer board Figure 2: ALTERA FPGA board Among all sections of PB 505 trainer board, what we are going to deal with are as follows: 1-­‐ Power supplies: The power supply is used to apply power to the ICs. Since we are going to work with TTL ICs, we just need the Ground and +5V. The fixed 5V supply has become an industry standard for powering digital TTL IC's. 2-­‐ Logic Indicators: Sixteen LED's, eight red and eight green, make up eight Logic Indicators that will display logic high and low conditions. In this lab you should always select +5 and TTL. The red ones turn on when there is a high voltage, which means “true” or 1. The green ones turn on when there is a low voltage, which conversely means “false” or 0. An unconnected input, or an input not at valid logic level, will cause both LED's to be extinguished. 3-­‐ Logic Switches: By using these switches you can apply logic 1 or logic 0 to the input pins of an IC. The selector must be on +5. 4-­‐ The Breadboards: The breadboard allows you to connect components and wire your circuits very easily and quickly. The breadboard consists of many holes for you to connect hook-­‐up wires and IC chips. Also, the leads or terminals of most of the components like resistors, diodes, transistors, etc. can be pushed straight into the holes. As you see in Figure 3 All of the holes are already connected together in groups. This way, you can connect two wires together (or connect a wire to an IC pin) simply by plugging the two wires into two holes that are already connected together. The holes in rows are linked horizontally and column holes are linked vertically. Figure 3. Breadboard internal connections. ( http://www.ldrengineering.org/building-­‐a-­‐circuit-­‐on-­‐breadboard/ In addition to your PC and trainer boards, you will see some other devices for each station. These are instruments which can be either input or output for our boards. Now, we introduce them briefly so that you know when you may need them 1-­‐ Generating Input voltages: Figure 4 shows the DC voltage supply and Figure 5 shows the AC function generator. They are inputs to our circuits. Figure 4: DC power supply Figure 5: Function generator 2-­‐ Watching output voltages: Figure 6 shows a Multimeter used to determine the value of DC signals or effective value of AC signals. By this Mutimeter you can be aware of the value of a steady signal (either voltage or current). However, if we are interested in observing the timing details of a signal, we should use an Oscilloscope, as seen in Figure 7, because it shows us the signal as it really is at any given moment. Figure6: Multimeter Figure7: Oscilloscope There are a bunch of 74XX ICs that contain basic gates such as And, Or, Nand, Nor, Xor, they vary in number of gates and also the input numbers for each gates within them. In Table 1 you can see some of them. Part number Description 7400 quad 2-­‐input NAND gate 7402 quad 2-­‐input NOR gate 7404 hex inverter 7405 hex inverter with open collector outputs 7408 quad 2-­‐input AND gate 7410 triple 3-­‐input NAND gate 7411 triple 3-­‐input AND gate Tabel 1: Some of 74 series ICs.( http://en.wikipedia.org/wiki/7400_series) Figure 8 shows a 7404 TTL integrated circuit. The IC has a marker on one end so you can determine the correct orientation. Every IC needs to be supplied with appropriate voltage in order to have energy to work properly. Figure8: 7404 IC As you see in Figure 9, The Pin 7 should be connected to GND and Pin 14 should be connected to +5V. The Other pins serve as inputs or outputs for one of the 6 Invert gates. Figure9: 7404 IC pin out Some general rules of circuit construction are provided here to help you efficiently complete laboratory assignments. 1. Be careful when inserting ICs into the breadboard sockets. If you do not put it in straight, it is very easy to crush the pin into a zigzag shape or fold the pins underneath the body of the IC. This will lead to a bad connection or no connection at all, and possibly destroy the chip. 2. Every once in a while try to touch some metal objects to discharge yourself of static electricity before handing ICs. 3. Pay attention to the power and ground connections on the IC. Reversing these connections will destroy the IC. Shorting power and ground may damage the power supply by overheating it. Never feed a TTL IC with a voltage more than 5V, it may damage the IC. 4. Always turn off the power when making connections, and turn it on only after you have finished making all of the connections. 5. ICs might feel slightly warm when working. However, if it is hot to the touch, turn off the power immediately and try to figure out what is wrong. If after inspecting your circuit you still cannot find the problem, notify the lab TA. 6. If a circuit fails to function, first check the power pins. Then use a multimeter to find the problem. You can start by checking the wires and then checking the voltages of IC pins. Sometimes this can be tedious, but it is worth it! If you construct your circuit neatly from the very beginning, it will help you a lot if debugging is needed. 7-­‐ After you are done, please put every piece in its place; remember your friend is going to use this lab right after you, and of course they do not want to waste their time on searching through your mess to find what they need. 8-­‐Prepare your lab report before the next session starts. No late homework is accepted. Write your name, lab section and lab report number at the top right corner of your report. Name: Aba Sade Class: L002 L#1 Lab Problems: 1-­‐ Connect a wire between SW1 and L1, Sw2 and L2 ,….. , Sw8 and L8. Record the state of LED for the data switch in the 1 position and 0 positions. 2-­‐ Place the 7404 IC in the breadboard as instructed. Test the IC; to check whether each Not gate is working properly, you must test the output state of each gate for all possible inputs (0 and 1). Please write the truth table for each gate as you test them (they should look like Figure 10). Figure10 : Truth table of a not gate 3-­‐ Cascade three gates and apply logic 1 to the input of the first gate. See the state of input and outputs of all other gates. Repeat with applying logic zero as the input. Write the truth table for this circuit. 4-­‐ Now find a 74XX IC that has AND gates ( you can google “2-­‐ input AND gate”) , then google the image of the IC showing the function of each pin. Now bring that IC to your desK and test one of its gates. Write the truth table for your tests. 5-­‐ Repeat the step 5 for a 74XX IC that has OR gates. Then do it with an IC with XOR gates. Write the truth tables for your tests. 6-­‐ If you think you are interested , try to mix a 7400 and a 7404 to produce AND Logic . Of course, you just need one invert gate from 7404 and one NAND gate from 7400. Can you build a NOR logic with these two ICs?